Topband: [Bulk] Re: ADC Overload from MW transmitters

[Jim Brown]

On Sat,10/24/2015 3:02 PM, Stephen Hicks, N5AC wrote:
> Simply my opinion here, but in my experience booth analog and digital can
> yield results that will please even the most discerning audiophile.

In the world of pro audio (those who make a living doing it) we say 
"audiophool," alternate spelling "audiofool."

> Generally, the things that go wrong are design errors that result in
> distortion.

Or a system that has inadequate headroom.

It's important to understand that devices operating in the digital 
domain produce different KINDS of distortion than do devices in the 
analog domain.  Clip in the analog domain is usually a gradual 
transition from linear behavior; the distortion products are intermod 
and harmonics. Intermod and harmonics are also present in nature -- most 
real objects that vibrate produce harmonics, and many produce intermod. 
The human voice and most musical instruments all fall into this 
category. As a result, the ear/brain views low order harmonics and 
intermod of audio frequencies as far more "natural" than higher order 
harmonics and intermod. ANY well-played instrument includes harmonics of 
the fundamental note being played -- it is PART of the instrument's 
natural sound.  There are, for example, musical "sound effects" units 
that intentionally produce second harmonic distortion of the input 
signal. The front panel control that sets the strength of the 2nd 
harmonic is called "warmth."

By contrast, clipping (overload) distortion in the digital domain is all 
of the digital bits at 1, which produces a high strength impulse (click) 
at the transition, no signal until the level drops below clip, and 
another click at the transition.  At the low signal end of an A/D 
converter, there are not enough bits to accurately describe the signal, 
so the digital signal produced is a poor copy of the analog signal. 
Digital distortions are NEVER natural, so are, in general, far more 
perceptible by the ear/brain than analog distortions.

73, Jim K9YC